Centrifugal pump



7 May 20, 1969 R. w. SUTTON 3,444,818

CENTRIFUGAL PUMP Filed Oct. 10, 1966 Sheet of 2 ROBERT W SUTTON INVENTORBUCKHOR/V, BL ORE, K LAROU/S T a SPAR/(MAN ATTORNEYS y 1969 R. w. SUTTQN3,444,818

CENTRIFUGAL PUMP Filed Oct. 10, 1966 Sheet 2 of 2 ROBERT W. SUTTONlNVE/VTOR BUC/(HOR/V, BLORE, KLAROU/ST 8 SPAR/(MAN ATTORNEYS UnitedStates Patent 3,444,818 CENTRIFUGAL PUMP Robert W. Sutton, Rte. 1, Box668, Wilsonville, Oreg. 97070 Filed Oct. 10, 1966, Ser. No. 585,535 Int.Cl. F04d 29/00, 1/04; B02c 18/40 US. Cl. 103111 Claims ABSTRACT OF THEDISCLOSURE A centrifugal pump for pumping mixtures of solids and liquidsincluding a housing defining an intake passage with annular inner andouter serrated cutting edges. Rotating blades of a chopper outside thehousing coact with the outer serrated edge to shred incoming solids to asize sufiicient to prevent clogging the intake passage, and radialcutting edges of impeller blades within the housing coact with the innerserrated edges to further reduce the size of solids to permit theirpassage through the pump. Inclined leading edges on the impeller bladesdirect solids toward the blade cutting edges.

The present invention relates to centrifugal pumps and more particularlyto such pumps for pumping a mixture of liquids and solids such asmanure, sewage and other waste materials.

Prior pumps designed especially for handling liquid borne solids havecommonly included a rotatable cutting element for shredding solids drawninto the pump chamher. In some prior pumps, the functions of shreddingand impelling have been combined in a single blade unit while in otherprior pumps the two functions have been performed by separate elements.Nevertheless, regardless of the design and the placement of the cuttingand impeller blades of prior pumps, solids, and particularly stringysolids such as straw, have had a tendency, once within the chamber, toaccumulate on the impeller and eventually clog the pump.

The pump of the present invention is an improvement over prior pumps forhandling mixtures of liquids and solids primarily in that it has animproved impeller that does not tend to collect solids within the pumpchamber and in fact that serves as a positive means for shredding solidsto an acceptable size within the chamber and impelling them toward thepumps discharge passage.

Accordingly, a primary object of the present invention is to provide anew and improved centrifugal pump that will not clog when pumpingmixtures of solids and liquids.

A more specific object of the invention is to provide a centrifugal pumpas aforesaid having an improved impeller for preventing the accumulationof solids within the pump.

Another specific object is to provide an improved impeller for a pump asaforesaid which also serves as an efiicient cutting element for reducingthe size of solids entering the pump chamber.

A further important object is to provide a pump as aforesaid with animproved stationary cutting edge con figuration for coaction with themovable cutting elements of the pump.

Still another object is to provide a pump as aforesaid having animproved preliminary chopper blade which is especially resistant to wearand which serves to lengthen the life of the stationary cutting elementwith which it coacts.

Other important objects are to provide a centrifugal pump as aforesaidwhich is economical to construct, operate and maintain.

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The above and other objects and advantages of the present invention willbecome more apparent from the following detailed description whichproceeds with reference to the accompanying drawings wherein:

FIG. 1 is an elevational view, partly in section, of a pump inaccordance with the invention;

FIG. 2 is a bottom end view taken along the line 22 of FIG. 1 with aportion of the outer casing broken away;

FIG. 3 is a horizontal sectional view taken along the line 33 of FIG. 1showing the pump impeller; and

FIG. 4 is a vertical sectional view taken along the line 4-4 of FIG. 3showing on an enlarged scale a portion of the impeller bladeconstruction.

With reference to the drawings FIG. 1 illustrates a pump 10 in itsvertically disposed operative position. The pump normally would bepositioned in a sump such as, for example, in a dairy barn for pumpingliquidfied manure. The pump includes a central driven shaft 12 whichextends upwardly from the main body of the pump to a connection with thedrive shaft of a suitable motor (not shown) at the upper end of thesump. The pump includes an outer casing consisting of a flanged uppershaft housing section 14 which is bolted to an intermediate casingsection 16, the lower end of which is in turn bolted to a lower casingsection 18. The lower casing section defines a main pump chamber 20housing an impeller 22 rotatable on the drive shaft 12.

The pump chamber is generally cylindrical in shape and is bounded at itsupper end by upper wear plate 24 and at its lower end by a lower wearplate 26. Lower wear plate 26 has a hub portion 28 which defines acentral intake passage 30 leading into the pump chamber. A peripheralportion of lower casing section 18 defines a tangential dischargepassage 32 leading from the chamber.

Impeller 22 is a one-piece member which includes a series of impellerblades 34 within the chamber and a hub portion 36 which extends througha central opening in the upper wear plate. Impeller hub 36 has an upperportion 37 of reduced cross section which is joined by a roll pin 38 tothe pump shaft 12 so that the impeller rotates with the shaft.Surrounding upper hub portion 37 is a keeper ring '40, the upper end ofwhich defines the lower extremity of a sealing chamber packed tightlywith packing material 42 so that water cannot rise above this pointbetween the outer casing and the shaft. The upper end of the packingchamber is bounded by a thin metal collar 44 which is retained in placeaxailly by the packing and by an upper sealing member 46. Above thispoint middle housing section 16 defines a bearing chamber 48 withinwhich a pair of axially spaced roller bearings 50 and 52 mount the pumpshaft and are retained by a retainer member 54. Retainer 54 has anannular oil passage 56 with periodic lateral passages 58 leading intothe bearing chamber so that the bearings can be conveniently oiledthrough an access passage (not shown) from outside the pump casing. Anupper bearing retainer 60 defines the upper end of the bearing chamberand is sealed at 61 at its juncture with the housing and at 62 at itsjuncture with the drive shaft. Thus the bearing chamber is sealedagainst liquids at both ends.

The pump shaft extends centrally through all three sections of the pumpcasing and projects out through intake openings 30 at its lower end. Achopper member 64 is fixed to the lower end of the shaft by a roll pin66. Referring especially to FIGS. 1 and \2, the chopper member includesa pair of opposed chopper blades 67, 68. The flat upper surfaces 69 ofthese blades wipe across an outer surface portion 70 of lower wear plate26 and across an outer scalloped cutting edge 71 at the intersection ofthe outer wear plate surface and the interior wall of the plate definingintake passage 30 so that the leading edges 72 of the blades chopincoming solids to an acceptable size before they enter the intakepassage. The lower surface 73 of each chopper blade is curved andstreamlined in a direction from its leading edge 72 to its trailingedge. Furthermore, the hub 74 of the chopper is slidably mounted onshaft 12 for movement within limits along the shaft from a positionwherein the chopper blades are in cutting relationship to scallopedcutting edge 71 to a position wherein the chopper blades are spaced fromsuch cutting edge. Thus, upon rotation of the chopper blades, fluid flowover the streamlined lower blade surfaces tends to lift the blades awayfrom the lower wear plate. However, when a large mass of solid materialis drawn toward the intake passage, the mass will strike the lowersurfaces of the chopper blades and thus force the blades upwardly intocutting relationship with scalloped cutting edge 71 to chop the mass toa size small enough to enter the intake passage without clogging it. Theforegoing chopper construction lengthens the life of both the lower wearplate and the chopper blades far beyond what their lives would normallybe if the blades were in constant cutting relationship with the outersurface of the wear plate. The limited axial play of the chopper alsoprovides a selfcompensating adjustment for blade and plate wear.

As is evident from FIG. 2, the entire length of the interior wall of thewear plate which defines intake passage 30 is scalloped so as to defineboth the outer scalloped cutting edge 71 with which the chopper bladescoact and also an inner scalloped cutting edge 76 at the juncture of theintake passage with the pump chamber. The inner cutting edge coacts withgenerally radial lower edges 78 of impeller blades 34 to shred solidswithin the pump chamber to a still smaller size so that they can bepassed between the impeller blades and out through discharge passage 32.The interior wall of wear plate 26 is tapered inwardly and upwardlytoward the pump chamber so that such wall intersects the inside surfaceof the wear plate at less than a right angle, thereby providing cuttingedge 76 with a more effective cutting angle.

With reference to FIGS. 3 and 4, each impeller blade is formed as anintegral part of the plate-like impeller unit 22 and curves in agenerally radial direction from a leading edge 80 at a central portionof the chamber to a trailing edge 82 adjacent the periphery of thechamber. The leading edge of each blade is beveled rearwardly to lessenthe resistance of such blades in passing through liquid and to reducethe tendency of solids to collect on such edge. The individual bladesare joined together by a web portion 84, as shown best in FIG. 3, whichextends parallel to and adjacent the top of the impeller chamber. Theimpeller unit has a central opening through which the pump shaft 12extends, and such opening is of a slightly larger diameter than that ofthe shaft. The impeller unit, including leading edges 80 of the impellerblades, is spaced from the shaft by an annular spacer member 86.

An important feature of the impeller blades is the rearward inclinationof leading edges 80 as shown best in FIG. 4. The inclination isrearwardly from the upper extremities of the blades to the intersectionof their leading edges and their radial cutting edges 78 adjacent thesealloped cutting edge 76. Thus the leading edges recede downwardly andrearwardly away from the pump shaft and toward stationary cutting edge76 so that solids which would otherwise tend to collect on such leadingedges are urged by centrifugal force downwardly along the leading edgesand against stationary cutting edge 76 where they are cut to sizes smallenough to pass between the impeller blades.

It should also be noted that the rearward inclination of leading edges80 of the impeller blades causes adjacent ones of such leading edges todiverge in a downward direction to define progressively increasingspaces between the leading edges in the same direction. Thus, solidswhich are too large to pass through the small spaces between blades atthe upper part of the chamber will be urged by centrifugal force downalong the diverging leading edges of the blades until the openingbetween blades widens sufficiently to pass the solids toward theperiphery of the chamber. If the solids are too large to pass betweenthe leading edges of the blades at their widest spacing, such solidswill eventually be thrown against scalloped cutting edge 76 and shearedto smaller sizes by the lower cutting edges of the impeller blades. Itis the foregoing described inclination and diverging nature of theleading edges of the impeller blades in cooperation with the sta tionaryscalloped cutting edge of the wear plate that contributes most to thepumps unique nonclogging action. This action is believed to beconsiderably superior to the nonclogging tendencies of prior pumpsdesigned for the same purpose.

Summarizing the operation of the pump, pump shaft 12 is driven, therebyrotating the impeller blades and the chopper blades simultaneously.Thus, liquid and liquid borne solids are drawn toward the intake passagewhere the spinning chopper blades reduce the size of excessively largesolid materials before they enter the intake passage. As the liquid andthe solids carried thereby reach the pump chamber they are impelled bythe impeller blades toward the periphery of the chamber and thence outthrough the discharge passage. However, if the solids reaching thechamber are unable to pass between the impeller blades at their leadingedges, they are thrown downwardly and rearwardly along such leadingedges and sheared to a reduced size sufficient to pass between theblades by the coaction of the lower edges of the impeller blades and thestationary scalloped inner cutting edge of the wear plate.

Another advantage of the pump as described is that the upper and lowerwear plates 24 and 26 can be replaced periodically as necessary withoutreplacing any other pump elements. This is done simply by removing thelower section 18 of the outer casing and then unbolting the lower wearplate from such section and unbolting the upper wear plate from themiddle section 16 of the casing.

Having described a preferred embodiment of the invention, it should beapparent to those having skill in the art that the invention permits ofmodification in arrangement and detail. I claim as my invention all suchmodifications as come within the true spirit and scope of the appendedclaims.

I claim:

1. A centrifugal pump for pumping a mixture of liquid and solid materialcomprising:

a housing including means defining a pump chamber and an intake passageopening into one end of said chamber, a closed opposite end and adischarge openmg,

means defining an inner cutting edge at the inner end of said intakepassage within said chamber and an outer cutting edge at the outer endof said intake passage outside said chamber,

impeller means rotatable within said chamber including impeller bladeshaving cutting edges in cutting relationship with said inner cuttingedge,

a chopper member including a chopper blade rotatable outside saidchamber in cutting relationship with said outer cutting edge,

a drive shaft extending through said chamber and mounting said impellermeans and said chopper member for rotation,

means mounting said chopper member on said shaft for axial slidingmovement along said shaft from a position in cutting relationship withsaid outer cutting edge to a position spaced from said outer cuttingedge,

said chopper blade having a broad outer surface facing away from saidouter cutting edge with a streamlined cross sectional configuration sothat fluid passing over said surface upon rotation of said chopper bladewill tend to lift said blade out of engagement with said outer cuttingedge and thereby prolong the life of both said blade and said edge.

2. A centrifugal pump comprising:

means defining a housing including a main pump chamber, an inlet openingand an outlet opening,

means defining an annular stationary cutting edge at the entrance of andin surrounding relationship to said inlet opening into said chamber,

impeller means rotatable within said chamber, including multipleimpeller blades, each having a generally radial cutting edge whichpasses in shear-cutting relationship across said annular stationarycutting edge upon rotation of said impeller means,

said radial cutting edge of each said blade intersecting a generallyaxially extending leading edge of said blade at a radial position nextadjacent said annular stationary cutting edge,

said leading edge of each blade extending from a position radiallyinwardly of and axially spaced from said stationary cutting edge andbeing inclined so as to recede in a direction proceeding from the axisof said impeller means toward said radial cutting edge and toward theperiphery of said chamber whereby solids drawn into said chamber areurged by water pressure and guided by said leading edges toward saidradial and annular stationary cutting edges,

said leading edges of adjacent impeller blades diverging from oneanother proceeding in a direction toward their respective radial cuttingedges so as to define spaces between said leading edges which becomeprogressively wider in a direction toward said radial cutting edges, themaximum width of said spaces between adjacent blades at the leadingedges of said blades being substantially less than the diameter of saidinlet and said outlet openings whereby solids too large to pass betweenadjacent leading edges are guided along said leading edges against saidstationary cutting edge so as to be reduced to a size small enough topass between said adjacent leading edges and through said pump chamber,

said annular stationary cutting edge being concentric with respect tothe axis of said impeller means and extending continuously about saidintake opening,

said annular continuous stationary cutting edge includingcircumferentially extending edge portions interupted at intervals byradially recessed cutting edge portions defining with saidcircumferential cutting edge portions a continuous scalloped cuttingedge.

3. A centrifugal pump comprising:

means defining a housing including a main pump chamber, an inlet openingand an outlet opening,

means defining a stationary cutting edge at the entrance of said inletopening into said chamber,

impeller means rotatable Within said chamber, including impeller bladeseach having a generally radial cutting edge which passes in cuttingrelationship said stationary cutting edge upon rotation of said impellermeans,

said radial cutting edge of each said blade intersecting a generallyaxially extending leading edge of said blade at a radial position nextadjacent said stationary cutting edge whereby said radial cutting edgedoes not extend appreciably radially inwardly of said stationary cuttingedge,

said leading edge of each blade extending from a position radiallyinwardly of and axially spaced from said stationary cutting edge andbeing inclined so as to recede in a direction proceeding from the axisof said impeller means toward said radial cutting edge and toward theperiphery of said chamber whereby solids drawn into said chamber areurged by said leading edges toward said radial and said stationarycutting edges,

means defining an intake passage having an outer cutting edge at theouter entrance end of said intake passage,

a chopper element rotatable outside said intake passage,

said chopper element including a chopper blade coacting with said outercutting edge to shred large solids before they enter said intakepassage.

4. A pump according to claim 3 wherein said means defining said intakepassage comprises a replaceable wear plate having a circumferentialseries of axially extending flutes extending the length of said intakepassage so as to define at the inner and outer ends of said passage,respectively, a serrated inner cutting edge for shearing coaction withsaid impeller blades and a serrated outer cutting edge for shearingcoaction with said chopper blade.

5. A pump according to claim .3 including a drive shaft extendingcentrally through said chamber for driving said impeller means and saidchopper, said chopper being mounted on said drive shaft for rotationtherewith but being slidable within limits axially of said shaft from aposition in cutting relationship with said outer cutting edge to aposition spaced from said outer cutting edge, said chopper blade havinga broad fiat surface facing said outer cutting edge and an oppositebroad surface facing away from said cutting edge, said opposite surfacebeing streamlined so that upon rotation of said blade fluid flow oversaid outer surface tends to lift said chopper blade away from said outercutting edge to prevent excessive wear of said outer cutting edge andsaid blade.

References Cited UNITED STATES PATENTS 2,050,104 8/1936 Lauchenauerl03--111.1 2,371,681 3/1945 Durolin 103111.1 1,763,595 6/1930 Paatsch103115 2,245,035 6/1941 Hartman l03111.1 2,658,453 11/1953 Walters105-11l.1

FOREIGN PATENTS 538,150 3/1955 Belgium.

542,597 5/ 1922 France. 1,377,185 9/1964 France.

HENRY F. RADUAZO, Primary Examiner.

U.S. C1. X.R.

